The invention concerns an apparatus for adjusting the inclination of a seat squab of a vehicle seat.
An apparatus of that kind is known from DE 30 22 950 A. The vehicle seat involves in particular a truck seat, a tractor seat, a stacking truck seat, or a seat for a building machine.
Usually, such adjusting apparatuses of the kind set forth in the opening part of this specification are integral components of the respective vehicle seat, that is to say in production of the corresponding vehicle seat they are integrated into same.
The object of the present invention is to provide an adjusting apparatus of the kind set forth in the opening part of this specification, which is also suitable for subsequent fitment, that is to say for subsequent combination with a vehicle seat, and which, while being of a relatively simple structural configuration, requires only a small amount of space in the heightwise direction of the vehicle seat.
In accordance with the invention, in an apparatus of the kind set forth in the opening part of this specification, that object is attained in that there is provided a rocker having an upper and a lower rocker element which are pivotably movably connected together by lateral bearing bushes, that fixed to the upper rocker element is a toothed bridge with mutually oppositely disposed bridge tooth arrangements which are concentric with respect to the bearing bushes, and that provided between the two bridge tooth arrangements of the toothed bridge are two toothed sliders with slider tooth arrangements facing away from each other and provided between the two toothed sliders is a locking member rotatable about a rotary axis extending through the bearing bushes, wherein the two toothed sliders are linearly movably guided on the lower rocker element between a locking position of engaging into the bridge tooth arrangements and a release and adjusting position spaced from the bridge tooth arrangements, the locking member is provided for adjustment of the two toothed sliders between the release and adjusting position and the locking position, and provided between the rotary axis and the lower rocker element is a prestressed spring element which urges the two toothed sliders self-lockingly into the locking position.
The rocker of the adjusting apparatus according to the invention, with the upper and the lower rocker elements, is advantageously only of a small structural height so that the rocker can be disposed without any problem between the seat squab of a vehicle seat and a seat springing arrangement which is usual in relation to such vehicle seats. By virtue of its small structural height, the apparatus according to the invention has scarcely any influence, or only an unnoticeable influence, on the overall height of the corresponding vehicle seat. By means of the adjusting apparatus according to the invention, the seat squab of a vehicle seat can be adjusted for example through an order of magnitude of xc2x112 degrees relative to the horizontal, in small angular steps. This appropriately involves adjustment about a transverse axis of the seat, which is defined by the rotary axis. By means of suitable adaptor components, it is also possible to embody inclination of the seat transversely with respect to the direction of travel, that is to say about a longitudinal axis of the seat.
It has proven desirable for the upper and the lower rocker elements to be in the form of sheet metal parts. Those sheet metal parts may involve deep-drawn or stamped parts which are simple and inexpensive to produce.
Structurally simple and highly reliable fixing of the toothed bridge to the upper rocker element is afforded if the toothed bridge is centered on the upper rocker element by centering projections and fixed by means of fixing elements spaced therefrom. Those fixing elements may involve fixing screws or preferably rivets. By virtue of the centering projections which are spaced from the fixing elements and which project without play into associated holes in the upper rocker element, the respective forces are reliably transmitted from the seat squab of the vehicle seat to the upper rocker element and thus to the rocker.
In order to permit so-called xe2x80x98sliding ratchetingxe2x80x99 when the inclination of the seat squab of the vehicle seat is adjusted as desired, it is desirable if the bridge tooth arrangements of the toothed bridge and the slider tooth arrangements of the toothed sliders have wave-shaped tooth profiles.
It has proven to be advantageous if, in the case of the adjusting apparatus according to the invention, each of the toothed sliders has a back which is towards the locking member and if the locking member is provided with diametrally mutually oppositely disposed noses which bear against the back. The noses of the locking member and the backs of the toothed sliders are preferably designed in such a way that subsequent adjustment of the toothed sliders is made possible by means of the mechanically prestressed spring element disposed between the rotary axis and the lower rocker element, so that, even after a long period of operation of the adjusting apparatus according to the invention, any play which possibly occurs between the bridge tooth arrangements of the toothed bridge and the slider tooth arrangements of the toothed sliders is eliminated or at least reduced.
It is desirable if the lower rocker element is provided with guide slots which are aligned with each other in a line and if the two toothed sliders for displacement thereof between the locking position and the release and adjusting position are provided with guide bars which are linearly movably guided in the guide slots.
Guide slots of that kind can be produced in a simple and highly precise manner in the lower rocker element. The guide bars are desirably integral component parts of the toothed sliders. That affords an exact and robust structure with excellent operational reliability.
It is particularly advantageous if the backs of the toothed sliders and the noses of the locking member are designed in such a way that, in the locking position of the toothed sliders, the noses lie on a straight operative line which extends through the rotary axis of the rocker and which extends parallel to the guide slots or is provided in coincident relationship therewith. That advantageously ensures that external mechanical forces which are introduced into the toothed bridge through the upper rocker element of the rocker and which by way of the bridge tooth arrangements exert a force component on the slider tooth arrangements of the toothed sliders do not urge the toothed sliders out of the locking position. That above-mentioned positioning of the toothed sliders on the straight operative line provides for reliably restraining the toothed sliders in the locking position.
In the adjusting apparatus according to the invention, a respective projection can extend away from each of the two toothed sliders and the locking member can be provided with mutually diametrally opposite sliding guides, by means of which the two toothed sliders are adjustable upon release adjustment of the locking member by the projections against the force of the spring element, from the locking position into the release and adjusting position.
The projections are desirably integral component parts of the toothed sliders. The sliding guides of the locking member can be in the form of sliding guide slots.
In the adjusting apparatus according to the invention the rotary axis is of a cross-section which differs from a circular shape. This may involve a quadrangular or square cross-section. The locking member of the locking apparatus according to the invention can have a through hole, the internal cross-section of which is adapted to the cross-section of the rotary axis. If however the adjusting apparatus according to the invention is used not just at one side of the respective vehicle seat but at both sides, then the two locking members can be actuated by means of a common rotary axis. Under given conditions, such as possible twisting of the rocker due to high external forces, the situation may involve non-uniform latching engagement of the toothed sliders on one side of the vehicle seat and on the other side. A rigid connection of the locking members can under some circumstances result in xe2x80x98latching beyondxe2x80x99, beyond the position of inclination of the vehicle seat that the seat occupant actually wants. In order to avoid such xe2x80x98latching beyondxe2x80x99, the locking member can have a through hole whose internal cross-section is adapted to the cross-section of the rotary axis in such a way that limited angular rotary movement of the rotary axis relative to the locking member is possible. Such a configuration of the last-mentioned kind has the advantage that the locking members which are individually sprung by virtue of the limited angular rotary movement are pivotable with each other in the release direction, but in the event of a locking position not being implemented on one of the two sides of the vehicle seat, they can assume their locking position independently of each other.
The adjusting apparatus according to the invention which comprises a small number of individual parts is advantageously simple to produce and assemble and it is of excellent operational reliability, while being of a simple and robust design. A further substantial advantage is that its range of angle or inclination adjustment is great, with a small overall structural height.
Adjusting apparatuses for a vehicle seat backrest which is adjustable in respect of its inclination are known for example from DE 35 40 726 C2, DE 38 10 612 C2, U.S. Pat. No. 5,918,714, EP 0 720 930 A1 or DE 198 16 248 C1. All those known adjusting apparatuses for the backrest of a vehicle seat, with a round basic structure, require a relatively large amount of space or base area. As such a known adjusting apparatus is disposed between the backrest and the seat squab of a vehicle seat, that need for base area is not particularly relevant and it has no effect whatsoever on the overall height of the vehicle seat.